Pivotal fluid valve assemblies are well-known in the art for a large variety of applications. For example, the prior art shows valve configurations in which an elongated arm, pivotal about a ball-and-socket arrangement, is connected at its distal, interior end to a valve-sealing head located inside the valve chamber. By manipulating the proximal, exterior end of the elongated arm, the arm can be caused to pivot about an intermediate point resulting in the valve-sealing head either engaging or disengaging a valve seat forming an inlet to or outlet from inside the valve chamber. Fluid flows freely through the valve chamber when the valve head is disengaged from the valve seat, but is stopped from flowing when the valve-sealing head engages the seat so as to seal off the orifice.
Representative of the prior art in this field is U.S. Pat. No. 2,313,128 (Densten). The Densten patent shows a fluid control valve for a water faucet in which an elongated arm 7 (see FIGS. 1-4), connected at one end to a spherical valve member 16, pivots about an intermediate semi-spherical pivot 6 that mates with a cupped washer or sealing element 5 made of rubber or similar elastic material. This is essentially a ball-and-socket arrangement which wears causing increasing mechanical tolerances which can ultimately result in the failure of the valve. Accordingly, instead of only two-directional (forward and back) pivoting, the Densten configuration permits essentially 360 degree rotation of arm 7 which, according to Densten, is advantageous because the valve element can "present a number of different surfaces to its seat and thus this valve element will not become gouged out or deformed due to repeated bearing at one point on said valve," (col. 1, lines 12-16).
U.S. Pat. No. 3,785,563 (Maple) shows a shut-off device for a traveling sprinkler system. As best seen in FIGS. 1 and 2, the valve portion of this device comprises an elongated arm 34, connected at one end to a spherical valve member 32, wherein arm 34 pivots about an intermediate spherical pivot 36 seated in an annular retainer member 52 and O-ring seal 54. As in the Densten patent, this is essentially a ball-and-socket arrangement which can wear resulting in increasing mechanical tolerances and ultimately failure of the valve assembly.
U.S. Pat. No. 1,794,703 (Methudy) shows a valve comprising an elongated valve stem 9 extending through a cap 10 and through a "diaphragm or seal 12 of flexible and pliable material such as leather or any other material or substance that will serve as an equivalent . . . " (page 1, lines 59-65). The "diaphragm" in Methudy is cup-shaped with the convex or outside portion of the cup surface projecting inwardly toward the interior of the valve. Stem 9 is not pivotal, but rather can be moved up or down to open or close the valve respectively by the manipulation of handle 23. Furthermore, in Methudy, seal 12 serves only to prevent leakage from the interior of the valve; it does not support stem 9 in any way. Instead, stem 9 is supported on screw 19 which, in turn, is supported on walls 4 and 5 by means of disc member 17.
A valve assembly which includes (1) a diaphragm which acts as a valve seal and (2) a pivot arm extending through the diaphragm is provided in a commercially available product by Burkert Contro-matic of Orange, Calif., as Burkert Type 300. The valve is a two position valve with its pivot arm being movable about a pivot axis above the diaphragm between an opened position wherein an outlet port is connected to a venting port, and a closed position wherein the venting port is closed and the inlet port is connected to the outlet port. The pivot arm is moved between the open and closed positions by an armature solenoid arrangement. The diaphragm is used solely as a seal to insure that material flowing through the valve does not interfere with the solenoid. Separate structure provided above the diaphragm (outside the fluid chamber) including a coil spring (which is used to kept the pressure outlet closed against the medium pressure) is provided to define the pivot axis about which the arm pivots and accordingly is subject to wear and increasing tolerances. Further, the structure does not provide, nor does it seem adequate to provide, accurate control of flow rate between the two open and closed positions. In addition, the construction of the diaphragm, which is shaped to cover the end of the pivot arm, necessitates the use of the elastomeric diaphragms, or costly metal shaped diaphragms due to the unusual shape of the diaphragm, and increases the swept wetted surface area within the valve chamber.
U.S. Pat. No. 4,359,204 (Williams) shows a diaphragm actuated-rod operated valve assembly characterized by a one-piece elastomeric valve-spring-seal member operated by a push rod. U.S. Pat. No. 2,852,041 (Stinson) shows a valve-like device for sampling fluid from a plurality of sources. Somewhat further removed from the pivotal fluid valve art are U.S. Pat. No. 4,995,589 (Adishian et al.) directed to a bellows valve, U.S. Pat. No. 4,832,078 (Szekely et al.) directed to a quick-action valve, and U.S. Pat. No. 2,709,431 (Curtis) directed to a hand-held body massaging device.
Friction between moving parts in these prior art assemblies results in increasing tolerances which may be unacceptable for many applications. Assemblies with longer life cycling are believed possible if the pivot about which a pivot arm moves to control the flow of fluid is frictionless. The frictionless pivot support can be made for applications which include the handling of corrosive or toxic materials without contamination, and with the swept wetted surface area within the chamber being as small as possible.